Led by University of Sydney researchers and published in The Lancet Child & Adolescent Health, this is the first population-based cohort study to assess both adult fertility and cancer risk after surgical correction (orchidopexy) for undescended testes in early childhood. The procedure moves an undescended testicle into the scrotum and permanently fixes it there.

“In addition to an increased risk of testicular cancer, we found that boys with undescended testes had decreased paternity and increased use of assisted reproductive technologies for infertility in later life,” said the University of Sydney’s Professor Natasha Nassar, the study’s senior author.

The study provides new evidence to support international guidelines recommending surgery before 18 months of age for boys with undescended testes to reduce the risk of both testicular cancer and infertility later in life.

However, compliance with the guidelines remains poor given that nearly half of all boys with undescended testes in Australia – and more than three-quarters worldwide – are operated on after 18 months of age, says the research team from the University of Sydney, Curtin University and the Telethon Kids Institute.

“Before this study, there was no evidence-based information on the impact of early surgery on the future risk of testicular cancer and infertility in adult males,” said study leader, Dr Francisco Schneuer of the University of Sydney.

“Early diagnosis, ongoing examination and monitoring by parents and health practitioners and timely referral to surgery of boys with undescended testes is important to ensure adherence with guidelines.

“Early surgery can reduce the risk of malignancy and male infertility, and ultimately has the potential to reduce future adult male reproductive disorders.”

Study details

This is a population-based cohort study of 350,835 boys born in Western Australia between 1970 and 1999. The cohort was followed until 2016 by linking to data registries for hospital admissions, birth defects, cancer, and assisted reproductive technologies.

Key findings

Boys with undescended testes had 2.4 times the risk of adult testicular cancer compared to unaffected boys

The risk of testicular cancer increased by 6 percent with each 6-month increase in age at time of surgery (orchidopexy)

Boys with undescended testes had a 20 percent lower chance of paternity in adulthood compared to unaffected boys, and were more than twice as likely to use assisted reproductive technology for infertility as adults.

Male reproductive disorders increasing worldwide

Undescended testes is the most common reproductive birth defect in infant boys. One in 100 boys are affected and will require surgery

Testicular cancer affects young men aged 20-40 years, is the second most common cancer in young men and while rare, has increased by 50 percent in the last 30 years

Male infertility is a major challenge, with 5–10 percent of men worldwide being infertile.